High voltage switch with isolated power

ABSTRACT

A high voltage switch comprising: a high voltage power supply providing power greater than about 5 kV; a control voltage power source; a plurality of switch modules arranged in series with respect to each other each of the plurality of switch modules configured to switch power from the high voltage power supply, and an output configured to output a pulsed output signal having a voltage greater than the rating of any switch of the plurality of switch modules, a pulse width less than 2 μs, and at a pulse frequency greater than 10 kHz.

BACKGROUND

Producing high voltage pulses with fast rise times and/or fast falltimes is challenging. For instance, to achieve a fast rise time and/or afast fall time (e.g., less than about 50 ns) for a high voltage pulse(e.g., greater than about 5 kV), the slope of the pulse rise and/or fallmust be incredibly steep (e.g., greater than 10¹¹ V/s). Such steep risetimes and/or fall times are very difficult to produce especially incircuits driving a load with high capacitance. Such pulse may beespecially difficult to produce using standard electrical components ina compact manner; and/or with pulses having variable pulse widths,voltages, and repetition rates; and/or within applications havingcapacitive loads such as, for example, a plasma.

SUMMARY

A high voltage switch is disclosed comprising: a high voltage powersupply having a voltage greater than 5 kV; a first switch modulecomprising: a first switch having a first voltage rating; a firsttransformer electrically coupled with a control voltage power source andelectrically coupled with the first switch, providing a voltage lessthan the first voltage rating; and a first switch trigger electricallycoupled with the first switch; a second switch module arranged in serieswith the first switch module, the second switch module comprising: asecond switch having a second voltage rating; a second transformerelectrically coupled with the control voltage power source andelectrically coupled with the second switch, providing a voltage lessthan the second voltage rating; and a second switch trigger electricallycoupled with the second switch, and an output configured to outputswitched pulses from the high voltage power supply where the outputpulse voltage is greater than either the first switch voltage ratingand/or the second switch voltage rating.

In some embodiments, the first switch trigger produces a trigger havinga rise time less than about 20 ns. In some embodiments, the switchedpulses have a frequency greater than about 40 kHz. In some embodiments,the switched pulses have a rise time less than about 75 ns. In someembodiments, the switched pulses have a fall time less than 100 ns. Insome embodiments, the period of time where the first switch is closedwhile the second switch is open is less than 1 ms. In some embodiments,the stray capacitance of the high voltage switch is less than about 100pF. In some embodiments, the stray inductance of either or both thefirst switch module or the second switch module less than 300 nH. Insome embodiments, the control voltage power source provides AC linevoltages and frequencies. In some embodiments, the control voltage powersource provides 120 VAC at 60 Hz. In some embodiments, the any one ofthe secondary windings may have a stray capacitance with the primary ofless than 100 pF.

In some embodiments, the high voltage switch may include a transformercore; and a plurality of primary windings wound around the transformercore, the plurality of primary windings being electrically coupled withthe control voltage power source, wherein the first transformercomprises the transformer core, the plurality of primary windings, and afirst plurality of secondary windings wound around the transformer core;and wherein the second transformer comprises the transformer core, theplurality of primary windings, and a second plurality of secondarywindings wound around the transformer core.

A high voltage switch is disclosed comprising: a high voltage powersupply providing power greater than about 5 kV; a control voltage powersource; a plurality of switch modules arranged in series with respect toeach other, each of the plurality of switch modules configured to switchpower from the high voltage power supply, each of the plurality ofswitch modules comprising: a switch having a collector, an emitter, anda gate; a transformer electrically coupled with the control voltagepower source and electrically or inductively coupled with the switch;and a gate trigger electrically coupled with the gate of the switch,wherein the switch is opened and closed based on a signal from the gatetrigger; and an output configured to output a pulsed output signalhaving a voltage greater than the rating of any switch of the pluralityof switches, a pulse width less than 2 μs, and at a pulse frequencygreater than 10 kHz.

In some embodiments, the pulsed output signal includes pulses having arate of rise greater than 10¹¹ V/s. In some embodiments, the one or moreswitch modules of the plurality of switch modules produce less than 50ns of jitter. In some embodiments, the output is coupled with a plasmaload.

In some embodiments, the transformer comprises a transformer core and asecondary winding, wherein the average gap between the transformer coreand the majority of the secondary winding is greater than 0.5 inches. Insome embodiments, the transformer comprises a transformer core, aprimary winding, and a secondary winding, wherein the average gapbetween the majority of the primary winding and the majority of thesecondary winding is greater than 0.5 inches.

In some embodiments, each switch module is configured to switch at least5 W of power. In some embodiments, the transformer comprises atransformer core and a secondary winding, wherein the secondary windingcomprises a plurality of wires having a cross section with a width tothickness ratio less than 3. In some embodiments, the gate triggercomprises an isolated fiber optic trigger.

Some embodiments may include a method comprising: closing a first switchof a plurality of switches, the plurality of switches comprising nswitches, while opening n−1 switches of the plurality of switches for afirst plurality of time, wherein the plurality of switches areelectrically coupled with a power supply that produces a high voltage Vthat is greater than 5 kV; outputting an output switched pulses with avoltage

$\frac{1}{n}V$on a load; closing a second switch of the plurality of switches whileopening n−2 switches of the plurality of switches for a second period oftime; outputting the output switched pulses with a voltage

$\frac{2}{n}V$on the load; closing a second-to-last switch of the plurality ofswitches while opening one switches of the plurality of switches for asecond-to-last period of time; outputting the output switched pulseswith a voltage

$\frac{n - 1}{n}V$on the load; closing an n^(th) switch of the plurality of switches foran n^(th) period of time; and outputting the output switched pulses witha voltage V on the load.

In some embodiments, one or more of the first period of time, the secondperiod of time, the second-to-last period of time, and the n^(th) periodof time are less than 100 ms. In some embodiments, the output switchedpulses have a rise time less than about 20 ns. In some embodiments, theoutput switched pulses have a frequency greater than about 10 kHz.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following Detailed Descriptionis read with reference to the accompanying drawings.

FIG. 1 is a block diagram of a high voltage switch with isolated poweraccording to some embodiments.

FIG. 2 is an image of high voltage switch according to some embodiments.

FIG. 3 illustrates an isolation transformer arrangement according tosome embodiments.

FIG. 4 illustrates an isolation transformer arrangement according tosome embodiments.

FIG. 5A illustrates a cross-section of a secondary winding according tosome embodiments.

FIG. 5B illustrates a cross-section of a secondary winding according tosome embodiments.

FIG. 5C illustrates a cross-section of a secondary winding according tosome embodiments.

FIG. 5D illustrates a cross-section of a secondary winding according tosome embodiments.

FIG. 6A illustrates an isolation transformer according to someembodiments.

FIG. 6B illustrates an end view of an isolation transformer according tosome embodiments

FIG. 7 is an image of an isolation transformer according to someembodiments.

FIG. 8 illustrates four 500 ns waveforms from a high voltage switch thatincludes sixteen IGBT switch modules.

FIG. 9 illustrates four 500 ns waveforms from a high voltage switch thatincludes sixteen SiC MOSFET switch modules.

FIG. 10A illustrates a 10 μs, 10 kV waveform from a high voltage switchthat includes sixteen IGBT switch modules with a 50 ohm load.

FIG. 10B illustrates a 500 kHz, 12 kV waveform with a 1 μs pulse widthfrom a high voltage switch that includes sixteen IGBT switch moduleswith a 200 ohm load.

FIG. 10C illustrates a 500 ns, 15 kV waveform from a high voltage switchthat includes sixteen IGBT switch modules with a 500 ohm load.

FIG. 11 is flowchart of a method for producing a multilevel waveformusing a high voltage switch according to some embodiments.

FIG. 12A illustrates an upward pulse-step waveform produced from a highvoltage switch according to some embodiments.

FIG. 12B illustrates a downward pulse-step waveform produced from a highvoltage switch according to some embodiments.

FIG. 13 is a circuit diagram of a high voltage etch system according tosome embodiments.

FIG. 14 shows example waveforms produced by the high voltage etchsystem.

FIG. 15 is a circuit diagram of a high voltage etch system according tosome embodiments.

DETAILED DESCRIPTION

A high voltage switch is disclosed. A high voltage switch may include ahigh voltage power supply, a plurality of switch modules arranged inseries, and an output configured to output switched pulses from thepower supply with voltages greater than 5 kV, with rise times less thanabout 100 ns, a rise greater than 10¹¹ V/s, a pulse width less than 2μs, and/or frequencies greater than about 10 kHz. In some embodiments,the plurality of switches may be trigged by respective gate drivercircuits that are electrically isolated from other components. In someembodiments, each switch module may include a switch (e.g., asolid-state switch) having a collector, an emitter, and a gate; or aswitch having drain, source, and gate; and/or a snubber circuit.

In some embodiments, the high voltage switch may include a plurality ofsolid-state switches arranged to collectively switch voltages from about10 kV to about 400 kV. In some embodiments, the high voltage switch mayswitch with frequencies up to about 2,000 kHz. In some embodiments, thehigh voltage switch may provide single pulses of varying pulse widthsfrom about 50 seconds down to about 1 nanosecond. In some embodiments,the high voltage switch may switch at frequencies greater than about 10kHz. In some embodiments, the high voltage switch may operate with risetimes less than about 20 ns. In some embodiments, the high voltageswitch may include fiber optic and/or control voltage isolation. In someembodiments, a plurality of high voltage switches may be electricallycoupled together in parallel.

As used throughout this document, the term “high voltage” may include avoltage greater than about 1 kV, 10 kV, 20 kV, 50 kV, 100 kV, 1,000 kV,etc.; the term “high frequency” may be a frequency greater than about 1kHz, 10 kHz, 100 kHz, 200 kHz, 500 kHz, 1 MHz, etc.; the term “highrepetition rate” may be a rate greater than about 1 kHz, 10 kHz, 100kHz, 200 kHz, 500 kHz, 1 MHz, etc., the term “fast rise time” mayinclude a rise time less than about 1 ns, 10 ns, 50 ns, 100 ns, 250 ns,500 ns, 1,000 ns, etc.; the term “fast fall time” may include a falltime less than about 1 ns, 10 ns, 50 ns, 100 ns, 250 ns, 500 ns, 1,000ns, etc.; the term “low capacitance” may include capacitance less thanabout 1.0 pF, 10 pF, 100 pF, 1,000 pF, etc.; the term “low inductance”may include inductance less than about 10 nH, 100 nH, 1,000 nH, 10,000nH, etc.; and the term short pulse width may include pulse widths lessthan about 10,000 ns, 1,000 ns, 500 ns, 250 ns, 100 ns, 20 ns, etc.

FIG. 1 is a block diagram of a high voltage switch 100 with isolatedpower according to some embodiments. The high voltage switch 100 mayinclude a plurality of switch modules 105 (collectively or individually105, and individually 105A, 105B, 105C, and 105D) that may switchvoltage from a high voltage source 160 with fast rise times and/or highfrequencies and/or with variable pulse widths. Each switch module 105may include a switch 110 such as, for example, a solid state switch.

In some embodiments, the switch 110 may be electrically coupled with agate driver circuit 130 that may include a power supply 140 and/or anisolated fiber trigger 145 (also referred to as a gate trigger or aswitch trigger). For example, the switch 110 may include a collector, anemitter, and a gate (or a drain, a source, and a gate) and the powersupply 140 may drive the gate of the switch 110 via the gate drivercircuit 130. The gate driver circuit 130 may, for example, be isolatedfrom the other components of the high voltage switch 100.

In some embodiments, the power supply 140 may be isolated, for example,using an isolation transformer. The isolation transformer may include alow capacitance transformer. The low capacitance of the isolationtransformer may, for example, allow the power supply 140 to charge onfast time scales without requiring significant current. The isolationtransformer may have a capacitance less than, for example, about 100 pF.As another example, the isolation transformer may have a capacitanceless than about 30-100 pF. In some embodiments, the isolationtransformer may provide voltage isolation up to 5 kV, 10 kV, 25 kV, 50kV, etc. An example arrangement of isolation transformers is shown inFIG. 3 and a single isolation transformer is shown in FIG. 4.

In some embodiments, the isolation transformer may have a low straycapacitance. For example, the isolation transformer may have a straycapacitance less than about 1,000 pF, 100 pF, 10 pF, etc. In someembodiments, low capacitance may minimize electrical coupling to lowvoltage components (e.g., the source of the input control power) and/ormay reduce EMI generation (e.g., electrical noise generation). In someembodiments, the transformer stray capacitance of the isolationtransformer may include the capacitance measured between the primarywinding and secondary winding.

In some embodiments, the isolation transformer may be a DC to DCconverter or an AC to DC transformer. In some embodiments, thetransformer, for example, may include a 110 V AC transformer.Regardless, the isolation transformer can provide isolated power fromother components in the high voltage switch 100. In some embodiments,the isolation may be galvanic, such that no conductor on the primaryside of the isolation transformer passes through or makes contact withany conductor on the secondary side of the isolation transformer.

In some embodiments, the transformer may include a primary winding thatmay be wound and/or wrapped tightly around the transformer core. In someembodiments, the primary winding may include a conductive sheet that iswrapped around the transformer core. In some embodiments, the primarywinding may include one or more windings.

In some embodiments, a secondary winding may be wound around the core asfar from the core as possible. For example, the bundle of windingscomprising the secondary winding may be wound through the center of theaperture in the transformer core. In some embodiments, the secondarywinding may include one or more windings. In some embodiments, thebundle of wires comprising the secondary winding may include a crosssection that is circular or square, for example, to minimize straycapacitance. In some embodiments, an insulator (e.g., oil or air) may bedisposed between the primary winding, the secondary winding, and/or thetransformer core.

In some embodiments, keeping the secondary winding far from thetransformer core may have some benefits. For example, it may reduce thestray capacitance between the primary side of the isolation transformerand secondary side of the isolation transformer. As another example, itmay allow for high voltage standoff between the primary side of theisolation transformer and the secondary side of the isolationtransformer, such that corona and/or breakdown is not formed duringoperation.

In some embodiments, spacings between the primary side (e.g., theprimary windings) of the isolation transformer and the secondary side ofthe isolation transformer (e.g., the secondary windings) can be about0.1″, 0.5″, 1″, 5″, or 10″. In some embodiments, typical spacingsbetween the core of the isolation transformer and the secondary side ofthe isolation transformer (e.g., the secondary windings) can be about0.1″, 0.5″, 1″, 5″, or 10″. In some embodiments, the gap between thewindings may be filled with the lowest dielectric material possible suchas, for example, vacuum, air, any insulating gas or liquid, and/or solidmaterials with a relative dielectric constant less than 3.

In some embodiments, the power supply 140 may include any type of powersupply that can provide high voltage standoff (isolation) and/or havelow capacitance (e.g., less than about 1,000 pF, 100 pF, 10 pF, etc.).In some embodiments, the control voltage power source may supply 120 VAC or 240 V AC at 60 Hz.

In some embodiments, each power supply 140 may be inductivelyelectrically coupled with a single control voltage power source (e.g.,as shown in FIG. 3 or FIG. 4). For example, the power supply 140A may beelectrically coupled with the power source via a first transformer; thepower supply 140B may be electrically coupled with the power source viaa second transformer; the power supply 140C may be electrically coupledwith the power source via a third transformer; and the power supply 140Dmay be electrically coupled with the power source via a fourthtransformer. Any type of transformer, for example, may be used that canprovide voltage isolation between the various power supplies.

In some embodiments, the first transformer, the second transformer, thethird transformer, and the fourth transformer may comprise differentsecondary winding around a core of a single transformer (e.g., as shownin FIG. 4). For example, the first transformer may comprise a firstsecondary winding, the second transformer may comprise a secondsecondary winding, the third transformer may comprise a third secondarywinding, and the fourth transformer may comprise a fourth secondarywinding. Each of these secondary winding may be wound around the core ofa single transformer. In some embodiments, the first secondary winding,the second secondary winding, the third secondary winding, the fourthsecondary winding, and/or the primary winding may comprise a singlewinding or a plurality of windings wound around the transformer core.

In some embodiments, the power supply 140A, the power supply 140B, thepower supply 140C, and/or the power supply 140D may not share a returnreference ground and/or a local ground.

The isolated fiber trigger 145, for example, may also be isolated fromother components of the high voltage switch 100. The isolated fibertrigger 145 may include a fiber optic receiver that allows each switchmodule 105 to float relative to other switch modules 105 and/or theother components of the high voltage switch 100, and/or, for example,while allowing for active control of the gates of each switch module105.

In some embodiments, return reference grounds and/or local groundsand/or common grounds for each switch module 105, for example, may beisolated from one another, for example, using an isolation transformersuch as, for example, the transformer arrangement shown in either FIG. 3or FIG. 4.

Electrical isolation of each switch module 105 from common ground, forexample, can allow multiple switches to be arranged in a seriesconfiguration for cumulative high voltage switching. In someembodiments, some lag in switch module timing may be allowed or designed(e.g., see FIG. 12A and FIG. 12B). For example, each switch module 105may be configured or rated to switch 1 kV, each switch module may beelectrically isolated from each other, and/or the timing of closing eachswitch module 105 may not need to be perfectly aligned for a period oftime defined by the capacitance of the snubber capacitor and/or thevoltage rating of the switch.

In some embodiments, electrical isolation may provide many advantages.One possible advantage, for example, may include minimizing switch toswitch jitter and/or allowing for arbitrary switch timing. For example,each switch 110 may have switch transition jitters less than about 500ns, 50 ns, 20 ns, 5 ns, etc.

In some embodiments, electrical isolation between two components (orcircuits) may imply extremely high resistance between two componentsand/or may imply a small capacitance between the two components.

Each switch 110 may include any type of silicon switching device suchas, for example, an IGBT, a MOSFET, a SiC MOSFET, SiC junctiontransistor, FETs, SiC switches, GaN switches, photoconductive switch,etc. The switch 110, for example, may be able to switch high voltages(e.g., voltages greater than about 1 kV), with high frequency (e.g.,greater than 1 kHz), at high speeds (e.g., a repetition rate greaterthan about 500 kHz) and/or with fast rise times (e.g., a rise time lessthan about 25 ns) and/or with long pulse lengths (e.g., greater thanabout 10 ms). In some embodiments, each switch may be individually ratedfor switching 1,200 V-1,700 V, yet in combination can switch greaterthan 4,800 V-6,800 V (for four switches). Switches with various othervoltage ratings may be used.

There may be some advantages to using a large number of lower voltageswitches rather than a few higher voltage switches. For example, lowervoltage switches typically have better performance: lower voltageswitches may switch faster, may have faster transition times, and/or mayswitch more efficiently than high voltage switches. However, the greaterthe number of switches the greater the timing issues that may berequired.

The high voltage switch 100 shown in FIG. 1 includes four switch modules105. While four are shown in this figure, any number of switch modules105 may be used such as, for example, eight, twelve, sixteen, twenty,twenty-four, etc. For example, if each switch in each switch module 105is rated at 1200 V, and sixteen switches are used, then the high voltageswitch can switch up to 19.2 kV. As another example, if each switch ineach switch module 105 is rated at 1700 V, and sixteen switches areused, then the high voltage switch can switch up to 27.2 kV.

In some embodiments, the high voltage switch 100 may include a fastcapacitor 155. The fast capacitor 155, for example, may include one ormore capacitors arranged in series and/or in parallel. These capacitorsmay, for example, include one or more polypropylene capacitors. The fastcapacitor 155 may store energy from the high voltage source 160.

In some embodiments, the fast capacitor 155 may have low capacitance. Insome embodiments, the fast capacitor 155 may have a capacitance value ofabout 1 μF, about 5 μF, between about 1 μF and about 5 μF, between about100 nF and about 1,000 nF etc.

In some embodiments, the high voltage switch 100 may or may not includea crowbar diode 150. The crowbar diode 150 may include a plurality ofdiodes that may, for example, be beneficial for driving inductive loads.In some embodiments, the crowbar diode 150 may include one or moreSchottky diodes such as, for example, a silicon carbide Schottky diode.The crowbar diode 150 may, for example, sense whether the voltage fromthe switches of the high voltage switch is above a certain threshold. Ifit is, then the crowbar diode 150 may short the power from switchmodules to ground. The crowbar diode, for example, may allow analternating current path to dissipate energy stored in the inductiveload after switching. This may, for example, prevent large inductivevoltage spikes. In some embodiments, the crowbar diode 150 may have lowinductance such as, for example, 1 nH, 10 nH, 100 nH, etc. In someembodiments, the crowbar diode 150 may have low capacitance such as, forexample, 100 pF, 1 nF, 10 nF, 100 nF, etc.

In some embodiments, the crowbar diode 150 may not be used such as, forexample, when the load 165 is primarily resistive.

In some embodiments, each gate driver circuit 130 may produce less thanabout 1000 ns, 100 ns, 10.0 ns, 5.0 ns, 3.0 ns, 1.0 ns, etc. of jitter.In some embodiments, each switch 110 may have a minimum switch on time(e.g., less than about 10 μs, 1 μs, 500 ns, 100 ns, 50 ns, 10, 5 ns,etc.) and a maximum switch on time (e.g., greater than 25 s, 10 s, 5 s,1 s, 500 ms, etc.).

In some embodiments, during operation each of the high voltage switchesmay be switched on and/or off within 1 ns of each other.

In some embodiments, each switch module 105 may have the same orsubstantially the same (±5%) stray inductance. Stray inductance mayinclude any inductance within the switch module 105 that is notassociated with an inductor such as, for example, inductance in leads,diodes, resistors, switch 110, and/or circuit board traces, etc. Thestray inductance within each switch module 105 may include lowinductance such as, for example, an inductance less than about 100 nH,10 nH, 1 nH, etc. The stray inductance between each switch module 105may include low inductance such as, for example, an inductance less thanabout 300 nH, 100 nH, 10 nH, 1 nH, etc.

In some embodiments, each switch module 105 may have the same orsubstantially the same (±5%) stray capacitance. Stray capacitance mayinclude any capacitance within the switch module 105 that is notassociated with a capacitor such as, for example, capacitance in leads,diodes, resistors, switch 110 and/or circuit board traces, etc. Thestray capacitance within each switch module 105 may include lowcapacitance such as, for example, less than about 1,000 pF, 100 pF, 10pF, etc. The stray capacitance between each switch module 105 mayinclude low capacitance such as, for example, less than about 1,000 pF,100 pF, 10 pF, etc.

Imperfections in voltage sharing can be addressed, for example, with apassive snubber circuit (e.g., the snubber diode 115, the snubbercapacitor 120, and/or the freewheeling diode 125). For example, smalldifferences in the timing between when each of the switches 110 turn onor turn off or differences in the inductance or capacitances may lead tovoltage spikes. These spikes can be mitigated by the various snubbercircuits (e.g., the snubber diode 115, the snubber capacitor 120, and/orthe freewheeling diode 125). This mitigation can allow for stepwise highvoltage waveforms as demonstrated in the stepping waveforms shown inFIGS. 12A and 12B.

A snubber circuit, for example, may include a snubber diode 115, asnubber capacitor 120, a snubber resistor 116, and/or a freewheelingdiode 125. In some embodiments, the snubber circuit may be arrangedtogether in parallel with the switch 110. In some embodiments, thesnubber capacitor 120 may have low capacitance such as, for example, acapacitance less than about 100 pF.

In some embodiments, the high voltage switch 100 may be electricallycoupled with or include a resistive load 165. The resistive load 165,for example, may have a resistance from 50 ohms to 500 ohms.Alternatively or additionally, the load 165 may be an inductive load.

FIG. 2 is an image of an example high voltage switch according to someembodiments. In this example, the high voltage switch includes aplurality of independent power inputs (e.g., power supplies 140), aplurality of fiber-optic triggers (e.g., isolated fiber trigger 145), aplurality of switch stages (e.g., switches 110), a plurality of snubbercomponents (e.g., the snubber diode 115, the snubber capacitor 120,and/or the freewheeling diode 125), a plurality of crowbar diodes (e.g.,crowbar diode 150), and a plurality of energy storage capacitors (e.g.,fast capacitor 155).

FIG. 3 illustrates a block diagram of an arrangement of isolationtransformers according to some embodiments. In this embodiment, aplurality of isolation transformers 320 (collectively or individually320, and individually 320A, 320B, 320C, 320D) may be electricallycoupled with a control voltage power source 305 and a plurality of gatedriver circuits 130. In some embodiments, the control voltage powersource 305 may include any power supply that can provide AC or DC powerto the isolation transformers 320 such as, for example, 120 V AC or 240V AC at 60 Hz. In some embodiments, the control voltage power source 305may provide power greater than 1 W, 10 W, 100 W, for example. In someembodiments, the control voltage power source 305 may provide a voltagegreater than 10 V, or 100 V, for example. In some embodiments, controlvoltage power source 305 may comprise one or more power supplies.

Each of the plurality of isolation transformers 320, may include atransformer core 330 (collectively or individually 330, and individually330A, 330B, 330C, 330D), a primary winding 315 (collectively orindividually 315, and individually 315A, 315B, 315C, 315D), and/or asecondary winding 310 (collectively or individually 310, andindividually 310A, 310B, 310C, 310D). Any number of isolationtransformers 320 may be used. The control voltage power source 305 maybe electrically coupled with each primary winding 315.

Each primary winding 315 may include any number of individual windingsof wire that are wound about a respective one of the transformer cores330. In some embodiments, the primary winding 315 may be tightly woundaround the transformer core 330. In some embodiments, the primarywinding 315 may include a conductive sheet that is wound, wrapped, ordraped around the transformer core but is not electrically coupled withthe transformer core 330.

In some embodiments, the secondary winding 310 may be wound around thetransformer core 330 with as much space between the transformer core 330and the secondary winding 310 as possible. For example, the secondarywinding 310 may pass through the center of the aperture in thetransformer core 330. In some embodiments, the secondary winding 310 maycomprise a bundle of wires with a small surface area such as, forexample, a bundle that has a circular cross-section (see FIG. 5A), asquare cross-section (see FIG. 5B), an elliptical cross-section (seeFIG. 5C), and/or a rectangular cross-section (See FIG. 5D). Variousother cross-sections may be used. The small surface area and/or thedistance from the center of the transformer core may, for example,result in a lower capacitance.

In some embodiments, the secondary winding 310 may be arranged relativeto the primary winding 315 with as much space between the primarywinding 315 and the secondary winding 310 as possible. In someembodiments, the primary winding 315 may comprise a bundle of wires witha small surface area such as, for example, a bundle that has a circularcross-section (see FIG. 5A), square cross-section (see FIG. 5B), anelliptical cross-section (see FIG. 5C), and/or a rectangularcross-section (See FIG. 5D). Various other bundle cross-sections may beused. The small surface area and/or the distance from the center of thetransformer core may, for example, result in a lower capacitance.

Each of the transformer cores 330, for example, may be a toroid-shapedcore, a square-shaped core, a rectangular-shaped core, or a rod-shapedcore. Each of the transformer cores 330 may be comprised of iron,ferrite, soft ferrite, MnZn, NiZn, hard ferrite, powder, nickel-ironalloys, amorphous metal, glassy metal, or some combination thereof.

In some embodiments, each of the isolation transformers 320 may have aneffective/equivalent capacitance (e.g., the stray capacitance betweenthe primary winding and the secondary winding) of less than about 100pF, 10 pF, 1 pF, etc.

In some embodiments, each secondary winding 310 may include a wire woundaround a respective one of the transformer cores 330. In this example,for each secondary winding 310, the ratio of the number of each windingaround the core to the number of primary winding 315 wound around thecore may determine the voltage delivered from each of the secondarywinding 310. In some embodiments, each secondary winding 310 may beelectrically coupled with a corresponding gate driver circuit 130.

In some embodiments, a ground of the control voltage power source 305 isnot electrically coupled with a common ground associated with each orany secondary winding 310 and/or a ground associated with each or any ofthe gate drivers 130. As another example, the common ground of thecontrol voltage power source 305, the ground of each secondary winding310 and/or the common ground associated with each of the gate drivers130 may float relative to each other.

FIG. 4 illustrates a block diagram of an isolation transformerarrangement according to some embodiments. The isolation transformer 420may be electrically coupled with a control voltage power source 305and/or a plurality of gate driver circuits 130. The control voltagepower source 305 may include any power supply that can provide AC powerto the isolation transformer 420. control voltage power source 305control voltage power source 305

The isolation transformer 420 may include a transformer core 430, aprimary winding 415, and/or a plurality of secondary windings 310.

In this example, the transformer core 430 comprises a rectangular shapedcore with an interior aperture having a first core leg 431 and a secondcore leg 432. The transformer core 430 may be comprised of iron,ferrite, soft ferrite, MnZn, NiZn, hard ferrite, powder, nickel-ironalloys, amorphous metal, glassy metal, or some combination thereof.

The control voltage power source 305 may be electrically coupled withthe primary winding 415. The primary winding 415 may include wires woundaround the first core leg 431 of the transformer core 430. In someembodiments, the primary winding 415 may be wound and/or wrapped tightlyaround the first core leg 431 of the transformer core 430. In someembodiments, the primary winding 415 may include a conductive sheet thatis draped around the first core leg 431 of the transformer core 430. Theprimary winding may be wrapped around any of the legs or sides of thetransformer core 430, and multiple primaries may be used in parallel.

In some embodiments, the isolation transformer 420 may have aneffective/equivalent capacitance of less than about 100 pF, 10 pF, 1 pF,etc.

In some embodiments, a plurality of different secondary winding 310 maybe wound around the second core leg 432 of the transformer core 430 orany leg or portion of the transformer core 430. Each secondary winding310 may include a wire that is wound a number of times around atransformer core 430. In this example, four different secondary winding310 are represented. Any number of secondary winding may be included.For each secondary winding, the ratio of the number of each windingaround the core to the number of primary winding 415 wound around thecore may determine the voltage delivered from each of the secondarywinding 310. In some embodiments, each secondary winding 310 may beelectrically coupled with a corresponding gate driver circuit 130. Asshown in FIG. 4, four secondary winding 310 are electrically coupledwith a respective one of four different gate driver circuit 130.

In some embodiments, the secondary winding 310 may be wound around thesecond core leg 432 of the transformer core 430 with as much spacebetween the transformer core 330 and the secondary winding 310 aspossible and/or with as much space between the primary winding 415 andthe secondary winding 310 as possible. For example, the secondarywinding 310 may pass through the center of the aperture in thetransformer core 430. In some embodiments, the secondary winding 310 maycomprise a bundle of wires with a small surface area such as, forexample, a bundle that has a circular cross-section (see FIG. 5A), asquare cross-section (see FIG. 5B), an elliptical cross-section (seeFIG. 5C), and/or a rectangular cross-section (See FIG. 5D). As anotherexample, the secondary winding may include a bundle of wires in arectangular cross-section (see FIG. 5D) where the effective width isless than twice the effective thickness, or an elliptical cross section(see FIG. 5C) where the width is less than twice the thickness, and/orany variation in between a rectangular and elliptical cross section.Various other bundle cross-sections may be used. The small surface areaand/or the distance from the center of the transformer core may, forexample, result in a lower capacitance.

In some embodiments, both primary winding 415 and the secondary winding310 may be wound around the same section or leg of the transformer core430. For example, both primary winding 415 and the secondary winding 310may be wound around the second core leg 432 of the transformer core 430.As another example, both primary winding 415 and the secondary winding310 may be wound around the first core leg 431 of the transformer core430. Any number of primary winding and secondary winding may be woundaround any of the sections of the transformer core 430. In someembodiments, there may be a large separation between the primary windingand the secondary winding. In some embodiments, the secondary windingare arranged to reduce the stray capacitance between the secondarywinding and the primary winding and/or between multiple differentsecondary winding. Minimizing the surface area of the secondary winding,for example, may help minimize the stray capacitance.

FIG. 5A illustrates a cross-section of a secondary winding 505 accordingto some embodiments. In this example, the bundle of wires comprising thesecondary winding may be arranged to have a circular-cross section orhexagonal-cross section.

FIG. 5B illustrates a cross-section of a secondary winding 510 accordingto some embodiments. In this example, the bundle of wires comprising thesecondary winding may be arranged to have a square-cross section.

FIG. 5C illustrates a cross-section of a secondary winding 515 accordingto some embodiments. In this example, the bundle of wires comprising thesecondary winding may be arranged to have an elliptical-cross section.

FIG. 5D illustrates a cross-section of a secondary winding 520 accordingto some embodiments. In this example, the bundle of wires comprising thesecondary winding may be arranged to have a rectangular-cross section.

In some embodiments, the cross-section of the secondary winding 520 mayhave a width and a length. In some embodiments, the width to thicknessratio may be less than 3.

FIG. 6A is an isometric view of an isolation transformer 600 (e.g.,isolation transformer 420) according to some embodiments. FIG. 6Billustrates a side view of the isolation transformer 600 according tosome embodiments. In some embodiments, isolation transformer 600 mayinclude transformer core 605, primary winding 610 wound about a portionof the transformer core 605, and eight secondary winding 615 wound aboutportions of the transformer core 605. Any number of secondary winding615 may be included. In this example, both the primary winding 610 andthe secondary winding 615 are wound about the same or substantially thesame segment of the transformer core 605. In other embodiments, theprimary winding 610 and the secondary winding 615 are wound about thedifferent or substantially different segments of the transformer core605.

The secondary winding 615 are wound around a portion or leg of thetransformer core 605 such that the distance between portions or segmentsor legs of the transformer core 605 and the secondary winding 615 aremaximized. In this example, the secondary winding 615 may pass throughthe center of the core aperture 625. The primary winding 610 may includeelectrical leads 611 and each of the secondary winding may includeelectrical leads 612.

FIG. 7 is an image of an isolation transformer 700 according to someembodiments. In this embodiment, the isolation transformer 700 includestwo primary windings 610 and three secondary windings 615. The twoprimary windings can be wired in series to double the voltage on theprimary winding. For example, if the two primary winding are wired inparallel and coupled to 120 VAC source, 120 VAC is applied to theisolation transformer. On the other hand, if the two primary winding arewired in series and 240 VAC source, 240 VAC is applied to the isolationtransformer. This transformer, for example, may work with any range ofinput voltages from 100 VAC to 240 VAC and/or 50 Hz to 60 Hz inputfrequencies. This may, for example, allows for use with any or all powergrids around the world, with the standardly available voltages.

In some embodiments, the ratio of the number of secondary winding to theratio of the number of primary winding can vary to produce a step-up ora step-down transformer. For example, with 120 VAC applied to theprimary winding an output of 19.7 V RMS may be output from each of thesecondary winding with a ratio of 6:1 primary winding to secondarywinding.

FIG. 8 illustrates four 500 ns waveforms from a high voltage switch thatincludes sixteen IGBT switch modules driving different loads. The topwaveform is from a high voltage switch driving a pulse across a 500 ohmload, the second to the top waveform is from a high voltage switchdriving a pulse across a 200 ohm load, the third waveform is from a highvoltage switch driving a 1 pulse across a 00 ohm load, and the bottom isfrom a high voltage switch driving a pulse across a 50 ohm load.

FIG. 9 illustrates four 500 ns waveforms from a high voltage switch thatincludes sixteen SiC MOSFET switch modules driving different loads. Thetop waveform is from a high voltage switch driving a pulse across a 500ohm load, the second to the top waveform is from a high voltage switchdriving a pulse across a 200 ohm load, the waveform is from a highvoltage switch driving a pulse across a 100 ohm load, and the bottomwaveform is from a high voltage switch driving a pulse across a 50 ohmload.

FIG. 10A illustrates a 500 kHz, 12 kV waveform with a 1 μs pulse widthfrom a high voltage switch that includes sixteen IGBT switch modulesdriving a pulse across a 200 ohm load.

FIG. 10B illustrates a 10 μs, 10 kV burst waveform from a high voltageswitch that includes sixteen IGBT switch modules driving a pulse acrossa 50 ohm load.

FIG. 10C illustrates a 500 ns, 15 kV waveform from a high voltage switchthat includes sixteen IGBT switch modules driving a pulse across a 500ohm load.

In some embodiments of high voltage switches including IGBT switches,the rise time of a pulse may depend on the load and/or the current. Insome embodiments of high voltage switches including IGBT switches, thefall time may depend inversely with the current.

In some embodiments, the high voltage switches may include any type ofswitch such as, for example, solid state switches, IGBT switches,photoconductive switches, GAN switches, silicon switches, siliconcarbide switches, etc.

FIG. 11 is flowchart of a process 900 for producing a multilevelwaveform using a high voltage switch according to some embodiments. Theprocess 900 includes a number of blocks that may be arranged orrearranged in any order. The process 900 may be used, for example, withthe high voltage switch 100.

The process 900 starts at block 905. At block 905, the counter, n, canbe set to one.

At block 910, n switches can be closed. At block 915, the remaining N-nswitches can be opened, where N equals the number of switches in thehigh voltage switch. In some embodiments, block 910 and 915 can occursimultaneously. If n=1, then a single switch will be closed while theremaining switches, N−1, will be open.

At block 920, a voltage

$\frac{n}{N}V$will be applied to the load, where V is the high voltage provided by thesuch as, for example, the high voltage source 160. For example, if n=1and N=12, then the voltage applied to the load is one-twelfth the highvoltage

$\left( {\frac{1}{12}V} \right).$

At block 925 the process 900 may pause for a period of time, T Theperiod of time, T, may, for example, be a time less than about 1 s, 500ms, 100 ms, 50 ms, 25 ms, 10 ms, 5 ms, etc. The maximum time period, T,may be less than a value determined by the value of the snubbercapacitor 120 associated with the switch being closed, the straycapacitance in the switch module 105, and/or the stray inductance in theswitch module 105. For example, the maximum time period, T, may be setas the amount of time it takes for the snubber capacitor charge prior toreaching the cutoff voltage of the switch such as, for example, 1 ms to100 ns.

In some embodiments, the snubber components may be sized to handle suchoperation where switches are opened and closed with varied timings andsequences. This may result in unusually large amounts of energy in thesnubber components in the snubber circuit. In some embodiments, thesnubber circuit may include switches and/or resistors that may be usedremove stored energy from the snubber circuit.

At block 930 it can be determined if the counter, n, is greater than orequal to the total number of switches, N. If the counter, n, is greaterthan or equal to the total number of switches, N, then process 900proceeds to block 940. If the counter, n, is not greater than or equalto the total number of switches, N, then process 900 proceeds to block935.

At block 935, the counter may be incremented and process 900 proceeds toblock 910, such as, for example, setting n=n+1. In some embodiments, thecounter may be incremented by any positive or negative integer such as,for example, one, two, three, four, five, etc. In some embodiments, thecounter may be incremented a different integer value during eachiteration.

At block 940, the output voltage is set to zero volts and at block 945the process 900 pauses for a second period of time, Y, For example, thesecond period of time, Y, may be equal to the period of time, T.Alternatively, the second period of time, Y, may be set to any period oftime greater or lesser than the period of time, T The output waveformproduced by the process 900 may include the waveform shown in FIG. 12B.

In some embodiments, the process 900 may step down the output pulsevoltage. For example, at block 930, it can be determined whether thecounter, n, is greater than zero. If the counter, n, is greater thanzero, then process 900 can proceed to block 930 where the counter, n, isdecremented by an integer (e.g., incremented by a negative integer). Ifthe counter, n, is zero, the process 900 can proceed to block 940. Theoutput waveform produced by the process 900 may include the waveformshown in FIG. 12B.

In some embodiments, a method can produce an upward pulse-step waveform(e.g., as shown in FIG. 12A) followed by producing a downward pulse-stepwaveform (e.g., as shown in FIG. 12B).

FIG. 12A illustrates an upward pulse-step waveform produced from a highvoltage switch according to some embodiments.

FIG. 12B illustrates a downward pulse-step waveform produced from a highvoltage switch according to some embodiments.

Unless otherwise specified, the term “substantially” means within 5% or10% of the value referred to or within manufacturing tolerances. Unlessotherwise specified, the term “about” means within 5% or 10% of thevalue referred to or within manufacturing tolerances.

FIG. 13 is a circuit diagram of a high voltage etch system 1300according to some embodiments. The high voltage etch system 1300 can begeneralized into five stages (these stages could be broken down intoother stages or generalized into fewer stages and/or may or may notinclude the components shown in the figure). The high voltage etchsystem 1300 may include high voltage switch and transformer stage 1301,a resistive output stage 1302, a lead stage 1303, a DC bias power supplystage 1304, and a load stage 1305.

In some embodiments, the high voltage etch system 1300 can producepulses from the power supply with voltages greater than 5 kV, with risetimes less than about 20 ns, and frequencies greater than about 130 kHz.

In some embodiments, the high voltage switch and transformer stage 1301can produce a plurality of high voltage pulses with a high frequency andfast rise times and fall times.

In some embodiments, the high voltage switch and transformer stage 1301can include one or more high voltage switches 100, which may include anyhigh voltage switch disclosed or described in this document.

In some embodiments, the load stage 1305 may represent an effectivecircuit for a plasma deposition system, plasma etch system, or plasmasputtering system. In some embodiments, the plasma etch system mayinclude effective components that represent the physics of the plasmaand or a wafer. The capacitance C2 may represent the capacitance of thedielectric material upon which a wafer may sit. The capacitor C3 mayrepresent the sheath capacitance of the plasma to the wafer. Thecapacitor C9 may represent capacitance within the plasma between achamber wall and the top surface of the wafer. The current source I2 andthe current source I1 may represent the ion current through the sheath.

In some embodiments, the load stage 1305 may represent a plasma typeload. In some embodiments, the plasma load may have a capacitance lessthan about 100 nF, 50 nF, 20 nF, 10 nF, etc.

In some embodiments, the resistive output stage 1302 may include one ormore inductive elements represented by inductor L1 and/or inductor L5.The inductor L5, for example, may represent the stray inductance of theleads in the resistive output stage 1302. Inductor L1 may be set tominimize the power that flows directly from the high voltage switch andtransformer stage 1301 into resistor R1.

In some embodiments, the resistor R1 may dissipate charge from the loadstage 1305, for example, on fast time scales (e.g., 1 ns, 130 ns, 50 ns,1300 ns, 250 ns, 500 ns, 1,000 ns, etc. time scales). The resistance ofresistor R1 may be low to ensure the pulse across the load stage 1305has a fast fall time t_(f).

In some embodiments, the resistor R1 may include a plurality ofresistors arranged in series and/or parallel. The capacitor C11 mayrepresent the stray capacitance of the resistor R1 including thecapacitance of the arrangement series and/or parallel resistors. Thecapacitance of stray capacitance C11, for example, may be less than 500pF, 250 pF, 1300 pF, 50 pF, 130 pF, 1 pF, etc. The capacitance of straycapacitance C11, for example, may be less than the load capacitance suchas, for example, less than the capacitance of C2, C3, and/or C9.

In some embodiments, a plurality of high voltage and transformer stages1301 can be ganged up in parallel and coupled with the resistive outputstage 1302 across the inductor L1 and/or the resistor R1. Each of theplurality of high voltage switch and transformer stages 1301 may eachalso include diode D1 and/or diode D6.

In some embodiments, the capacitor C8 may represent the straycapacitance of the blocking diode D1. In some embodiments, the capacitorC4 may represent the stray capacitance of the diode D6.

In some embodiments, the DC bias power supply stage 1304 may include DCa voltage source V1 that can be used to bias the output voltage eitherpositively or negatively. In some embodiments, the capacitor C12isolates/separates the DC bias voltage from the resistive output stageand other circuit elements. It allows for a potential shift from oneportion of the circuit to another. In some applications the potentialshift it establishes is used to hold a wafer in place. Resistance R2 mayprotect/isolate the DC bias supply from the high voltage pulsed outputfrom the high voltage switch and transformer stage 1301.

FIG. 14 shows example waveforms produced by the high voltage etch system1300. In these example waveforms, the pulse waveform 1405 may representthe voltage provided by the high voltage switch and transformer stage1301. As shown, the pulse waveform 1405 produces a pulse with thefollowing qualities: high voltage (e.g., greater than about 4 kV asshown in the waveform), a fast rise time (e.g., less than about 200 nsas shown in the waveform), a fast fall time (e.g., less than about 200ns as shown in the waveform), and short pulse width (e.g., less thanabout 300 ns as shown in the waveform). The waveform 1410 may representthe voltage at the surface of a wafer represented in circuit 1300 by thepoint between capacitor C2 and capacitor C3 or the voltage acrosscapacitor C3. The pulse waveform 1415 represent the current flowing fromthe switch and transformer stage 1301 to the plasma. The circuit 1300may or may not include either or both diodes D1 or D2.

During the transient state (e.g., during an initial number of pulses notshown in the figure), the high voltage pulses from the switch andtransformer stage 1301 charge the capacitor C2. Because the capacitanceof capacitor C2 is large compared to the capacitance of capacitor C3and/or capacitor C1, and and/or because of the short pulse widths of thepulses, the capacitor C2 may take a number of pulses from the highvoltage switch to fully charge. Once the capacitor C2 is charged thecircuit reaches a steady state, as shown by the waveforms in FIG. 14.

In steady state and when the switch S1 is open, the capacitor C2 ischarged and slowly dissipates through the resistive output stage 1310,as shown by the slightly rising slope of waveform 1410. Once thecapacitor C2 is charged and while the switch S1 is open, the voltage atthe surface of the wafer (the point between capacitor C2 and capacitorC3) is negative. This negative voltage may be the negative value of thevoltage of the pulses provided by the high voltage switch andtransformer stage 1301. For the example waveform shown in FIG. 14, thevoltage of each pulse is about 4 kV; and the steady state voltage at thewafer is about −4 kV. This results in a negative potential across theplasma (e.g., across capacitor C3) that accelerates positive ions fromthe plasma to the surface of the wafer. While the switch S1 is open, thecharge on capacitor C2 slowly dissipates through the resistive outputstage.

When the switch S1 is closed, the voltage across the capacitor C2 mayflip (the pulse from the high voltage switch 100 is high as shown inwaveform 1405) as the capacitor C2 is charged. In addition, the voltageat the point between capacitor C2 and capacitor C3 (e.g., at the surfaceof the wafer) changes to about zero as the capacitor C2 charges, asshown in waveform 1410. Thus, the pulses from the high voltage switch100 produce a plasma potential (e.g., a potential in a plasma) that risefrom a negative high voltage to zero and returns to the negative highvoltage at high frequencies, with fast rise times, fast fall times,and/or short pulse widths.

In some embodiments, the action of the resistive output stage, elementsrepresented by the resistive output stage 1302, that may rapidlydischarge the stray capacitance C1, and may allow the voltage at thepoint between capacitor C2 and capacitor C3 to rapidly return to itssteady negative value of about −4 kV as shown by waveform 1410. Theresistive output stage may allow the voltage at the point betweencapacitor C2 and capacitor C3 to exists for about % of the time, andthus maximizes the time which ions are accelerated into the wafer. Insome embodiments, the components contained within the resistive outputstage may be specifically selected to optimize the time during which theions are accelerated into the wafer, and to hold the voltage during thistime approximately constant. Thus, for example, a short pulse with fastrise time and a fast fall time may be useful, so there can be a longperiod of fairly uniform negative potential.

Various other waveforms may be produced by the high voltage etch system1300.

In some embodiments, a bias compensation subsystem can be used to adjustthe chucking voltage in a semiconductor fabrication wafer chamber. Achucking voltage can be applied to the chuck to track the on/off patternof the pulse bias generator bursts, for example, so that there is aconstant voltage difference.

FIG. 15 is a circuit diagram of a high voltage etch system 1500according to some embodiments. In some embodiments, the high voltageetch system 1500 may include a high voltage switch 1405 coupled across ablocking diode D7 at, near or within the resistive output stage 1302 andor the DC bias power supply stage 1304.

In some embodiments, the high voltage switch 1405 may be open while theswitch 1410 is pulsing and closed when the switch 1410 is not pulsing.While closed, the high voltage switch 1405 may, for example, shortcurrent across diode D7. Shorting this current may allow the biasbetween the wafer and the chuck to be less than 2 kV, which may bewithin acceptable tolerances. The switch 1410 may be any power supplysuch as, for example, a high voltage switch 100, a nanosecond pulser, anRF power supply, etc.

Various embodiments are disclosed. The various embodiments may bepartially or completely combined to produce other embodiments.

Numerous specific details are set forth herein to provide a thoroughunderstanding of the claimed subject matter. However, those skilled inthe art will understand that the claimed subject matter may be practicedwithout these specific details. In other instances, methods, apparatusesor systems that would be known by one of ordinary skill have not beendescribed in detail so as not to obscure claimed subject matter.

The use of “adapted to” or “configured to” herein is meant as open andinclusive language that does not foreclose devices adapted to orconfigured to perform additional tasks or steps. Additionally, the useof “based on” is meant to be open and inclusive, in that a process,step, calculation, or other action “based on” one or more recitedconditions or values may, in practice, be based on additional conditionsor values beyond those recited. Headings, lists, and numbering includedherein are for ease of explanation only and are not meant to belimiting.

While the present subject matter has been described in detail withrespect to specific embodiments thereof, it will be appreciated thatthose skilled in the art, upon attaining an understanding of theforegoing, may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, it should be understoodthat the present disclosure has been presented for purposes of examplerather than limitation, and does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

That which is claimed:
 1. A high voltage switch comprising: a highvoltage power supply having a voltage greater than 5 kV; a first switchmodule comprising: a first switch having a first voltage rating; a firsttransformer electrically or inductively coupled with a control voltagepower source and electrically or inductively coupled with the firstswitch, providing a voltage less than the first voltage rating; and afirst switch trigger electrically or inductively coupled with the firstswitch; a second switch module arranged in series with the first switchmodule, the second switch module comprising: a second switch having asecond voltage rating; a second transformer electrically or inductivelycoupled with the control voltage power electrically or inductively andelectrically coupled with the second switch, providing a voltage lessthan the second voltage rating; and a second switch trigger electricallyor inductively coupled with the second switch, wherein the second switchtrigger is independently triggered relative to the first switch trigger,and a plasma electrically or inductively coupled with the first switchmodule and/or the second switch module, the plasma having a capacitanceless than about 20 nF, and the plasma receiving pulses from the highvoltage power supply greater than either the first switch voltage ratingand/or the second switch voltage rating.
 2. The high voltage switchaccording to claim 1, wherein the first switch trigger produces atrigger having a rise time less than about 20 ns.
 3. The high voltageswitch according to claim 1, wherein the switched pulses have afrequency greater than about 40 kHz.
 4. The high voltage switchaccording to claim 1, wherein the switched pulses have a rise time lessthan about 75 ns.
 5. The high voltage switch according to claim 1,wherein the switched pulses have a fall time less than 100 ns.
 6. Thehigh voltage switch according to claim 1, wherein the period of timewhere the first switch is closed while the second switch is open is lessthan 1 ms.
 7. The high voltage switch according to claim 1, wherein thestray capacitance of the high voltage switch is less than about 100 pF.8. The high voltage switch according to claim 1, wherein the strayinductance of either or both the first switch module or the secondswitch module less than 300 nH.
 9. The high voltage switch according toclaim 1, wherein the control voltage power source provides AC linevoltages and frequencies.
 10. The high voltage switch according to claim1, wherein the control voltage power source provides 120 VAC at 60 Hz.11. The high voltage switch according to claim 1, further comprising afirst plurality of secondary windings and a first plurality of primarywindings having a stray capacitance between the first plurality ofsecondary windings and the first plurality of primary windings is lessthan 100 pF.
 12. The high voltage switch according to claim 1, furthercomprising: a transformer core; and a plurality of primary windingswound around the transformer core, the plurality of primary windingsbeing coupled with the control voltage power source, wherein the firsttransformer comprises the transformer, the plurality of primarywindings, and a first plurality of secondary windings wound around thetransformer; and wherein the second transformer comprises thetransformer, the plurality of primary windings, and a second pluralityof secondary windings wound around the transformer.
 13. A high voltageswitch comprising: a high voltage power supply providing power greaterthan about 5 kV; a control voltage power source; a plurality of switchmodules arranged in series with respect to each other, each of theplurality of switch modules configured to switch power from the highvoltage power supply, each of the plurality of switch modulescomprising: a switch having a collector, an emitter, and a gate, and avoltage rating; a transformer electrically or inductively coupled withthe control voltage power source and electrically or inductively coupledwith the switch; and a gate trigger electrically or inductively coupledwith the gate of the switch, wherein the switch is opened and closedbased on a signal from the gate trigger; and an output configured tooutput a pulsed output signal having a voltage greater than the ratingof any switch of the plurality of switch modules, a pulse width lessthan 2 μs, and at a pulse frequency greater than 10 kHz; wherein eachgate trigger of each of the plurality of switch modules areindependently triggered.
 14. The high voltage switch according to claim13, further comprising a plasma electrically or inductively coupled withthe output and having a capacitance less than about 20 nF.
 15. The highvoltage switch according to claim 13, wherein the pulsed output signalincludes pulses having a rate of rise greater than 10¹¹ V/s.
 16. Thehigh voltage switch according to claim 13, wherein one or more switchmodules of the plurality of switch modules produce less than 50 ns ofjitter.
 17. The high voltage switch according to claim 13, wherein theoutput is electrically or inductively coupled with a plasma load. 18.The high voltage switch according to claim 13, wherein the transformercomprises a transformer core and a secondary winding, wherein theaverage gap between the transformer core and the majority of thesecondary winding is greater than 0.5 inches.
 19. The high voltageswitch according to claim 13, wherein the transformer comprises atransformer core, a primary winding, and a secondary winding, whereinthe average gap between the majority of the primary winding and themajority of the secondary winding is greater than 0.5 inches.
 20. Thehigh voltage switch according to claim 13, wherein each switch module isconfigured to switch at least 5 W of power.
 21. The high voltage switchaccording to claim 13, wherein the transformer comprises a transformercore and a secondary winding, wherein the secondary winding comprises aplurality of wires having a cross section with a width to thicknessratio less than
 3. 22. The high voltage switch according to claim 13,wherein the gate trigger comprises an isolated fiber optic trigger. 23.A method comprising: closing a first switch of a plurality of switches,the plurality of switches comprising n switches, while opening n−1switches of the plurality of switches for a first plurality of time,wherein the plurality of switches are electrically and/or inductivelycoupled with a power supply that produces a high voltage V that isgreater than 5 kV; outputting an output switched pulses with a voltage$\frac{1}{n}V$ on a load; closing a second switch of the plurality ofswitches while opening n−2 switches of the plurality of switches for asecond period of time; outputting the output switched pulses with avoltage $\frac{2}{n}V$ on the load; closing a second-to-last switch ofthe plurality of switches while opening one switches of the plurality ofswitches for a second-to-last period of time; outputting the outputswitched pulses with a voltage $\frac{n - 1}{n}V$ on the load; closingan n^(th) switch of the plurality of switches for an n^(th) period oftime; and outputting the output switched pulses with a voltage V on theload.
 24. The method according to claim 23, wherein the load comprises aplasma having a capacitance less than about 20 nF.
 25. The methodaccording to claim 23, wherein one or more of the first period of time,the second period of time, the second-to-last period of time, and then^(th) period of time are less than 100 ms.
 26. The method according toclaim 23, wherein the output switched pulses have a rise time less thanabout 20 ns.
 27. The method according to claim 23, wherein the outputswitched pulses have a frequency greater than about 10 kHz.
 28. Themethod according to claim 23, wherein the output wherein one or more ofthe first period of time, the second period of time, the second-to-lastperiod of time, and the n^(th) period of time are less than 5 ms.